Amsterdam stock exchange will no longer include penny stocks in its indices from next March, when parent company NTSE Euronext introduced new rules, the Financieele Dagblad reports.

Amsterdam has three indices: the AEX with 25 blue-chip companies, the Midkap and the AScX. The new rules mean that shares which do not rise above €1 for three months after March 2014 will not be eligible for inclusion in an index.

Shares which are already in an index must have an average price of at least 50 cents over three months, the FD said.

Penny stocks are ‘easy to manipulate, and index-based investors are forced to invest in them,’ George Patterson, director of NYSE Euronext’s European indices told the paper. In some cases, transaction costs are higher than the price, Patterson said.

Amsterdam has 11 penny stocks, two of which risk being removed from an index. Pharming, which closed at €0.126 on Wednesday is in the Midkap index while Kardan (€0.329) is listed in the AScX.